Mufflers, for example for motor vehicles, often include inserts for dividing and silencing the pulsating flow of exhaust gas. Generally, to provide appropriate silencing, and at the same time a reasonably low pressure drop, such inserts have to be relatively complex and large. To be able to reduce the dimensions of the muffler while maintaining its silencing capacity, fiber inserts, usually constituted of mineral fibers, can be provided in the muffler. The life of such mineral fiber inserts, however, is too short in relation to the life-expectancy of the structure of the muffler itself, especially if it is made of stainless steel, or other corrosion-resistant material. Another drawback of known mufflers is that, normally, different constructions and dimensions of the mufflers have to be available for different engine types.
This invention relates to an exhaust gas muffler, particularly for combustion engines, comprising a tubular envelope, a gas inlet at one end of the envelope, a gas outlet at the other end of the envelope, and between these ends, at least one muffler insert which includes two, or several, spaced apart cones of sheet metal, whose edges substantially closely contact the envelope, and whose axes of symmetry are substantially coaxial to the axis of the envelope.
An object of the present invention is to provide a muffler of simple construction, which without fiber inserts, and without causing unfavorable pressure drop of the exhaust gases, can be manufactured with relatively small dimensions, and at the same time have excellent silencing capacity.
Another object of the present invention is to provide a muffler which can be manufactured of only a few parts, and produced largely automatically, or at least with a simplified assembling procedure.
Still another object of the present invention is to provide a muffler of standard construction, which in a simple manner, by small modifications of its components, can be adapted to different types of engines.
The above-mentioned objects are achieved in mufflers of the above-described type by the fact that at least one sheet metal cone of each insert has at least one or a small number of relatively large gas flow passages, and that the centers of the passages adjacent cones are angularly separated, and that each insert is disposed with the apices of the cones directed toward the muffler outlet, and that adjacent cones of an insert are disposed at a distance from one another such that the apex of the rear cone, as viewed in the direction of the the gas flow, lies downstream of a plane perpendicular to the direction of the axis through the surface of abutment to the envelope of the front cone.